Oil spillage accidents lead the use of oil dispersants to break oil into small droplets to prevent oil coming ashore. Meanwhile, recent and rapid drop in surface pH could have devastating consequences to marine environment. However, their combined effects on marine species have not been experimentally evaluated. This study evaluated the toxicity of oil dispersant in the shrimp Litopenaeusvannameiunder pH 6.5 and 8.5. Healthy post larvae L. vannameiwere exposed to dispersant solution at concentration of 0%, 3%, 6%, 12% and 24% for 72 hours to determine mortality. Probit analysis was used to determine LC50, while the PAH of dispersant solution was characterized using GCMS method. The dispersant had negative effects to L. vannamei and that toxicity of dispersant increased over time and exposure concentration. The 72-h LC50 were equivalent to 191.18 mgL-1 and 553 mgL-1 for pH 6.5 and 8.5 respectively in which that dispersant is practically non-toxic to the shrimps. However, the combination of dispersant and lower pH increases the mortality of the shrimp; thus ocean acidificationmay increase dispersant accumulation in the L. vannamei tissue via surface contacting.